Daijiro Kodama

Mass-produced color graphic arts holograms

We have been developing various types of holograms. In this paper mass-produced color graphic arts holograms are discussed. The TRUE IMAGETM hologram, as it is known in Japan, is a volume-type hologram which diffracts selected wavelengths of the ambient light to selected desired angles. When replicating the TRUE IMAGETM, three lasers are used simultaneously or independently. There are four beneficial characteristics of the TRUE IMAGETM hologram; (1) Repeatable mass product techniques and few defects: a direct lamination method has been developed. (2) Looking bright and clear under fluorescent light: specially designed masters and replication conditions allows TRUE IMAGETM holograms to be seen under fluorescent light. (3) Stable chromaticities: expressing full color by developing objects, paints, mastering process and replication process. (4) Good environmental stability: use of effective adhesive films. In this paper, the first characteristic is mainly discussed.

Mastering process for color graphic arts holograms

We have been developing holograms and holography technology for more than two decades for various applications. Embossed-type holograms manufactured by NDP are commercially available and are used widely in Japan. Currently, we are developing volume-type holograms. Some holographic optical elements (HOEs) and color graphic-arts are ready for commercialization. We are studying color holograms are ready for commercialization. We are studying color holograms as the next generation of volume-type holograms. At the previous SPIE meeting, we reported on the process for mass producing full-color Loppmann holograms and the adhesive film employed. This paper concerns the mastering process. It should be simple so as to be suitable for mass production, and a hologram copied from a master should have limited viewing range so as to provide greater brightness. To obtain a brighter hologram with the desired viewing angle, we employ a new modified Denishuku method for mastering. In this study, the relationship between the incident angles used for mastering and for copying was examined, and a new way of limiting the viewing area was devised. Through a combination of our mastering, replication and adhesive technologies, we have succeeded in mass production full- color holograms for the first time in the world. This has enabled DNP to develop commercial-level color graphic-arts holograms, some of which are widely available in the marketplace.

Development of peripheral materials for color graphic arts holograms

Dai Nippon Printing is the first company in the world to succeed in the mass production of full-color 3D Lippmann type holograms, which are marketed under the name of TRUE IMAGETM. TRUE IMAGETM labels consist of a panchromatic photopolymer material and pressure-sensitive adhesives (PSAs). This new medium is expected to have wide application in various fields, such as publishing, labels for authentication, and so on. For commercial use, TRUE IMAGETM labels require high-quality PSAs. In this study, two new PSAs and a new layer structure were developed. One PSA provides TRUE IMAGETM labels with good environmental stability, and the other adjusts the playback wavelengths. These two PSAs together with a new layer structure have enabled the development of a new type of TRUE IMAGETM label for security applications.

Holographic light-control film for liquid crystal displays

We have been developing various holographic optical elements (HOEs) and holograms. In this paper holographic light control films (HLCFs) for use with reflective monochromatic type liquid crystal displays (LCDs) are discussed. The HLCFs are volume type holograms which diffract selected wavelengths of the ambient light to specific angles. Using HLCFs as reflectors in conjunction with LCDs allows the concentration of reflected light to specific viewing areas. Three beneficial characteristics of HLCFs, weak dependence upon incident light angles, good control of diffracted color and excellent environmental stability are described. (1) Weak dependency on incident light angles: Specially designing master holograms and replication conditions allows the production of HLCFs only depend weakly on the angle of the incident light. (2) Control of diffracted color: Varying process conditions allows the creation of HLCFs which diffract specific colors. (3) Stability during and after environmental tests: Using DuPont photopolymers resulted in good stability for both low and high temperatures and high humidity test conditions. In addition, the TEM pictures of the cross sections were shown.

50.4: Invited Paper: Rear Projection Screen with Improved Wider Vertical Viewing Angle

We developed a new rear projection screen compriseding of two total internal reflecting prism sheets laminated to each other in a 90 degree angle. The advantages of this screen are not only wider vertical viewing angle, but improved black level, the uniformity of color temperature, reduced scintillation, and reduced ghost images.